Some known full width arrays (FWA) have a common pixel density spanning across multiple chips in a single dimension or direction. Formation of such FWAs involves a process of using chips where pixel-to-edge distance is minimal, e.g., less than 4 microns, in the one dimension array plane, followed by using “active” die alignment/placement with minimal chip gap, typically ranging from 2-8 microns. The foregoing technique decreases reliance on wafer yield.
Some conventional methods for forming a two-dimensional (2D) image array include using a single chip, e.g., fabricated in a single lithographic process, and in some cases for very large arrays, a single chip is formed per wafer. See for example, sensor array 40 on wafer 42 depicted in FIG. 1. Some of these methods lead to the need for larger diameter wafers, so that higher resolution is obtainable. These methods result in very few chips formed per wafer, e.g., sometimes as few as one chip per wafer. Unfortunately, defects on a wafer may lead to scrapped chips, and in some circumstances, results in scrapping an entire wafer.
Conventional dicing and die placement methods, i.e., when chips are placed next to each other, often results in inconsistencies in the distance between pixels at the ends or edges of the chips. These inconsistencies create spaces and/or gaps in an image captured with such chip arrays that must be filled in, i.e., corrected for, using computer software. Moreover, some information could be lost in these gaps.
In other assemblies, chips are stacked on top of each other or positioned relative to a board resulting in large gaps therebetween. Tolerances of board alignment, die bonding alignment and dicing accuracy can collectively result in large gaps. The foregoing circumstances cause tolerance issues that do not allow many chips to be placed close together without unacceptable gap sizes.
The present disclosure addresses a system and method for forming large area arrays without increased material scrap rates, thereby minimizing costs associated with forming the same.